Y.com.sb died, so I edited my entire-YT-channel downloader:
https://rentry.org/4ehu6fm3 ( d80014c8845b4d4eaaa3165b95a73e456dfb5ead )

This branch of the code works locklessly, but depends on these websites to work: web.archive.org=static,critical and invidious.protokolla.fi=less-critical.

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How to find PMVs: search for popular songs. More likely to find one if it somewhat makes sense to be a pony music video. Of course this doesn't work on all tracks. For example, this track which is popular and doesn't heavily convey a message (lyrics are basically fluff) = no PMV:
>https://invidious.reallyaweso.me/watch?v=pIgZ7gMze7A - title="Wham! - Wake Me Up Before You Go-Go (Official Video)"